Assessment tasks should primarily reflect the nature of the discipline or subject but should also ensure that students have the opportunity to develop a range of generic skills and capabilities.
Assessment influences learning behaviours and shapes the experience of students, signalling what is important, focusing student effort and providing opportunities for feedback. Appropriate assessment should be an integral part of the learning process and should promote learning as well as evaluating how well students have achieved intended learning outcomes. If you expect students to evidence employability skills through assessment, then this means they would be embedded in the learning outcomes (alignment). However, you might wish to design assessment that provides opportunities for students to develop additional skills or attributes which are not assessed; in this case assessment functions as learning. For example, as part of their assessment your students might be asked to produce a video but you will not necessarily be assessing their editing skills per se.